What is the meaning of "b'Ein Tachbulos Yipal Am"?
Rashi: When affliction comes on Yisrael, and they do not put to heart to understand, fast and repent, the nation will fall.
R. Yonah: People of Chachmas Lev and thoughts are needed to conduct the nation, to guard from every pretext and see outcomes. If their enemies will plot a matter, he must find how to guard from it. Strategies come from Binah - "v'Navon Tachbulos Yikneh" (1:5).
Malbim: Without Tachbulos (refer to 11:14:2:1), the nation will fall in war.
Here it says "b'Ein Tachbulos Yipal Am." Below, it says "Machashavos b'Etzah Sikon uv'Sachbulos Ase Milchamah" (20:18)!
Malbim: Etzah is what Tevunah agrees to, what he chooses. Machashavah thinks about all possibilities; there are many - "Rabos Machashavos b'Lev Ish va'Atzas Hashem Hi Sakum" (19:21). As long as one did not decide, he wavers like foam on breaking waves of Machashavos. If he decided, he has a base. This is for worldly matters, e.g. business and income. It is not enough in war, for also the enemy has Etzah. Perhaps his Etzah will not succeed against the enemy's, like Chushai ha'Archi criticized Achitofel's counsel! Tachbulah is a bind of many Etzos. He ties rope to rope, causes and effects, so whatever the enemy does, there is counsel against it.
How is "Teshu'ah b'Rov Yo'etz"?
R. Yonah: Via many opinions, one will find the proper opinion to be saved from imminent danger.
Malbim: For war, many counselors are needed; each gives a different Etzah. Each Etzah has place in war; sometimes if one Etzah does not work against the enemy, another one will. This is a Mashal for an inner war against the internal enemy (the Yetzer ha'Ra).
